![[personal profile]](https://www.dreamwidth.org/img/silk/identity/user.png){kind=small}
You heard it here first!
At the big Lepton-Photon Conference in Chicago this morning (3pm UK time), the Belle Collaboration announced that they had discovered a large discrepancy between matter-antimatter asymmetries seen in two decays of the B-meson: the newly measured decay to phi + Ks, compared to the well-measured J/psi + Ks. The Standard Model of Particle Physics says these should have the same asymmetry, but Belle measured almost the opposite value.
This is just the sort of thing we have been looking for, because the Standard Model does not allow enough "CP violation" asymmetry to explain why the universe is made of matter, with no antimatter. Some other models allow for larger asymmetries that do provide such an explanation, though it is too early to say whether this measurement, even if it is confirmed, supports one of those models.
This is a controversial result because, in the same talk, the speaker presented the results from the BaBar collaboration (my experiment :-) . Our measurement of the same asymmetry, with similar accuracy, is compatible with the Standard Model, and incompatible with the Belle result. One of us will be left with egg on our faces - though if Belle turns out to be right, we'll really kick ourselves for missing such a significant result.
Before you get too excited (well maybe you weren't), I should say that such "over three sigma" effects come along every few years, and then go away as better measurements are made. The Standard Model has survived 30 years against some extremely stringent tests (most conducted by my previous experiment at LEP). However this is the first discrepancy in the CP violating sector, where (unless the cosmologists come up with a better idea) we know that something has to give.
You can find links to a press release, conference slides (which includes the BaBar result), and the paper at the top of the Belle home page. The result is so hot, that the press release has tomorrow's date (13 August) due to the timezone difference!
At the big Lepton-Photon Conference in Chicago this morning (3pm UK time), the Belle Collaboration announced that they had discovered a large discrepancy between matter-antimatter asymmetries seen in two decays of the B-meson: the newly measured decay to phi + Ks, compared to the well-measured J/psi + Ks. The Standard Model of Particle Physics says these should have the same asymmetry, but Belle measured almost the opposite value.
This is just the sort of thing we have been looking for, because the Standard Model does not allow enough "CP violation" asymmetry to explain why the universe is made of matter, with no antimatter. Some other models allow for larger asymmetries that do provide such an explanation, though it is too early to say whether this measurement, even if it is confirmed, supports one of those models.
This is a controversial result because, in the same talk, the speaker presented the results from the BaBar collaboration (my experiment :-) . Our measurement of the same asymmetry, with similar accuracy, is compatible with the Standard Model, and incompatible with the Belle result. One of us will be left with egg on our faces - though if Belle turns out to be right, we'll really kick ourselves for missing such a significant result.
Before you get too excited (well maybe you weren't), I should say that such "over three sigma" effects come along every few years, and then go away as better measurements are made. The Standard Model has survived 30 years against some extremely stringent tests (most conducted by my previous experiment at LEP). However this is the first discrepancy in the CP violating sector, where (unless the cosmologists come up with a better idea) we know that something has to give.
You can find links to a press release, conference slides (which includes the BaBar result), and the paper at the top of the Belle home page. The result is so hot, that the press release has tomorrow's date (13 August) due to the timezone difference!
